(May 2013) With technology producing more and cheaper ways to determine the sex of a fetus, fewer girls are being born—an estimated 1.5 million of them every year. They are sometimes referred to as the “missing” girls, the ones who were never born because of the premium some societies place on boys. This preference for sons and ease of determining sex before birth, along with a growing trend toward smaller families, have up-ended nature’s balance between males and females.

Prenatal sex selection was once thought to be unique to India and China, but the trend is now seen in other countries in South and East Asia as well as in Eastern Europe, and it could emerge in Africa in the not too distant future, according to to the Population Reference Bureau’s policy brief When Technology and Tradition Collide: From Gender Bias to Sex Selection.

Key Facts

Even without sex selection, more boys are born than girls. Normally, for every 100 baby girls, somewhere between 102 and 107 boys are born. This slight imbalance is due to biological and other factors.

In at least nine countries, the ratio of boy babies to girl babies is 110 or more. China is at the top of the list, with 118 boys born for every 100 girls, followed by Azerbaijan, Armenia, Georgia, Montenegro, Albania, Vietnam, India and Pakistan.

Why Sons?

Son preference is motivated by economic, social, and/or religious factors.

In strict patrilineal societies, inheritance of property, names, or titles comes through the male relatives, and earnings and labor of a son accrue to his parents. Girls are expected to live with and support her husband’s family after marriage. Economically, therefore, parents view spending on sons a better investment than in daughters.

Where dowries are customary, the bride’s family gives money, property or other goods to the groom’s family.

In some societies, sons play important roles in religious customs and rites, and men can take on public roles and responsibilities not open to women.

Advances in Technology

Technologies introduced in the 1970s that allowed for identification of fetal sex in utero have become increasingly become more affordable, less technically demanding, and less invasive.

Ultrasound is the most common method, and is used to determine sex at around 16 weeks of pregnancy. It became prevalent in developing countries in the 1980s. It is not invasive and can be performed by nonmedical personnel at low cost. As the equipment is becoming smaller and more mobile, it is more accessible in rural areas.

A simple, low-cost blood test has been proven to be 98 percent reliable after the 7th week of pregnancy.

Unintended Consequences

In areas where many more boys than girls are born, there becomes a shortage of women, which means there are fewer brides available for the large number of prospective grooms.

Promising Approaches

Many countries—including India, China, South Korea, Nepal, and Vietnam—have introduced laws restricting the use of technology for sex determination purposes.

Some medical organizations are working to promote codes of professional conduct related to the use of technology for sex determination and selection.

Laws and policies have been introduced promoting the rights and status of women and girls, including financial incentives to parents of girl children and more equitable property and inheritance rights.

Mass media campaigns in the form of TV and radio programs have focused on gender equality and the consequences of sex selection.